There was a time at school when I would try to write as good an essay as possible. Obviously your grammar had to be good. I used to take tourists on a tour for money, that helped me in my pronunciation a lot. Probably I overdid it, I tried to copy their accent, too. Then I got a job in India. My coworkers said I had an accent and they'd laugh. "Did you not learn speaking English at school?" The friends were from South India, and I could have sworn they had their own accent, too.
Then I came to the US. Again my coworkers were from South India. They'd speak to us as if we were Tamils, too. Man, I heard "DDDD ...DDDD...". I would watch the Yankies swirl their eyeballs when the colleagues would talk to them.
I think it's important to be able to get yourself across, for that you need to learn a few aspects of the language. But while talking in a foreign language, I think it is OK if you make a few mistakes. The reality is, there are exceptions to all rules in this world, and in language semantics. As long as the listeners can get what you are trying to convey, who cares about the others! I just say to myself, "Nobody has ever been perfect".